I unplugged my tcc solenoid a couple months ago and I'm now ready to take on the job of replacing it. However, I'm now wondering if it was the problem at all. It would engage almost immediately after shifting into 3rd gear. This would happen EVERY time I drove no matter what speed I was going! Most posts say the solenoid is bad because it stays locked up, but mine would always unlock while slowing down. The problem was it engaging before it was needed, sometimes at 25mph. It also seemed to rapidly engage and disengage around 30mph, like it wasn't sure if it should engage or not. Could this be a computer problem? Anyone have any thoughts on this? Thanks in advance. Tony
Originally posted by devilsidol: ...It also seemed to rapidly engage and disengage around 30mph, like it wasn't sure if it should engage or not. Could this be a computer problem? Anyone have any thoughts on this? Thanks in advance. Tony
Did it cause the car to vibrate and shake? If so, I've got the same question!
The TCC locks at 32 MPH and unlocks at 30 MPH unless someone changed it in a chip for you. 25-30 MPH does sound low (assuming your speedo is right). If it unlocks when you let off the throttle or when you lightly press the brake (RPM goes up some) then the ECM is doing it's job.
The problem come when the ECM tells the TCC to unlock and it doesn't. You come to a stop and it stalls the engine (beginning with a bunch of jerking and complaining from the drivetrain). It's like stopping with a manual trans with the clutch engaged.
Get the car up to 40 on flat ground, hold the throttle steady and slightly depress the brake (while holding the throttle). The RPM's should rise 200 RPM or more. Then release the brake and a second or two later the RPM's will drop as the TCC locks.
Next, press the throttle down about an 1" or so more than the cruise position, the TCC should unlock and you will speed up.
Next, back off on the throttle until you are back down the 40MPH and then press the throttle to hold 40MPH. The TCC should lock again.
If that is working, the TCC is fine and the ECM is fine.
TK
[This message has been edited by TK (edited 02-02-2006).]
Yes it definately unlocks when I let off the gas. And around 30mph if I press the gas it engages like it's in 5th gear on a stick. So I take it the ECM is okay and the soleniod is bad? Maybe worn out to where it engages too early? Again I don't have a problem with it when I come to a stop...it disengages fine.
Mine either does this at around 30mph or 40mph and only sometimes. Is it possible that the Torque Convertor is messed up? I hope not, lol, don't feel like pulling her all apart again:0
[This message has been edited by FierosinKY (edited 02-02-2006).]
It can't engage by itself. The ECM has to tell it to engage. When they are bad they typically won't disengage and hang in the on mode. I don't recall a bad TCC that would just go on all by itself but once it's on they won't go off.
If that makes sense.
Frankly you haven't said anything that makes me think the TCC or ECM is bad. The slight difference in MPH is a little off.
What year and engine is the car? Why did you disconnect the TCC in the first place?
Bad torque converter? Could be but that is really rare.
TK
[This message has been edited by TK (edited 02-02-2006).]
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06:09 PM
tharvey Member
Posts: 453 From: Blaine Wa 98231 US Registered: Jun 2005
I had my chip re-programmed and had the lock up changed to 39 mph from a previous 45 mph reading
Mine works fine and unless there was a shift kit in the car I do not know why it would lock up at 32mph, this seems reaaly low especially if going up any incline.
A easy fix sugestion might be to put a 2 pole single throw switch in-line with the switch, this way you would control when the converter would actually lock up and could dis-engage it inside the vehicle rather then removing the switch off the transmission.
I know they are cheap and easy to do, I am just waiting for some warm weather to do mine and also change the 3-2 switch and put in a shift kit.
Sounds like yours is working fine.
The programming of the chip is relatively easy to do especially if you have the prom burner.
Would be interesting to find out what the problem is
okay this isn't normal operation for the solenoid. I have had my car for ten years and it just recently started this. I drive along at forty mph and it is engaged. It won't disengage when I hit the gas until I push down enough for it to downshift to second gear. Then NO MATTER WHAT SPEED, if I'm in third gear it will engage. I unplugged it because it would cycle between engaged and disengaged and will never let me cruise at speeds between 25-45 Mph. Once I get passed 45mph then it stops cycling. I have an 86 GT V6. Maybe the switch is bad?
Another thing I should mention is that with it unplugged the car runs great (except for gas mileage). I recently plugged it in again and it didn't have a problem until the car was warmed up (about twenty minutes into city driving). Does the throttle position sensor tell the computer when to disengage the TCC? How does the computer know to disengage it when you are throttling up? I guess I could try and replace the throttle position sensor first to see if that helps.
Well I was going to replace the solenoid and switch, but I went to my local transmission shop and they said the parts are $189! I read somewhere that they were only about $60 for the switch, solenoid, and gasket. Anyone know a place that has them cheaper? At that price I might leave it alone till summer. Thanks again for the replies!
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01:37 PM
PFF
System Bot
jetman Member
Posts: 7789 From: Sterling Heights Mich Registered: Dec 2002
Originally posted by devilsidol: okay this isn't normal operation for the solenoid. I have had my car for ten years and it just recently started this. I drive along at forty mph and it is engaged. It won't disengage when I hit the gas until I push down enough for it to downshift to second gear. Then NO MATTER WHAT SPEED, if I'm in third gear it will engage. I unplugged it because it would cycle between engaged and disengaged and will never let me cruise at speeds between 25-45 Mph. Once I get passed 45mph then it stops cycling. I have an 86 GT V6. Maybe the switch is bad?
Unfortunately the ECM makes the speed decision. If your third-gear switch were bad, it would just open the possibility of engaging the TCC while in second (if you somehow managed to go 40mph smoothly at 20% throttle without the brake on in second). That's the trick. In order for it to engage, all the conditions have to be met: 1) no brake 2) third gear 3) no more than about 1/3rd throttle and a relatively constant speed. If the TCC were engaging randomly, it would continue to happen with it unplugged, because you don't get a circuit unless all that happens.
Ruling out the brake switch and the third-gear switch and the TCC itself, all you're left with is the ECM. Check the chip, make sure it's the righ one for your car. Here's the table:
Thanks jetman! Just what I was looking for. My ECM chip matches with the table you gave, Badger. However, you posted that one necessary element was the throttle being no more than 1/3 down for the TCC to engage. What sensor supplies this info? If it is malfunctioning and always reading 1/3 or less, then the TCC would engage in third gear at every speed. But then again mine also engages whether I've kept a steady speed or not. I'm assuming the speed sensor relates that info to the ECM, and since my speedo works it's not likely that it's the problem. I will try to get another ECM to test and post the results.
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03:15 AM
FieroFanaticFromHolland Member
Posts: 174 From: Hedel, Gelderland, The Netherlands Registered: Mar 2003
The sensor that "sense" trottle given, is the TPS, Trottle Position Sensor, but I think you will have other symtons too when the TPS is not working/ or only read less than 1/3...
Several questions, all related to auto tranny in '86 GT. Newbie so if questions are dumb, please cut me some slack. Quest in all this is to (a) reduce rpm/mile and (b) get better gas milage.
Comparing: '85 GT bought new, lockup vs non-lockup was about 300rpm at 60mph. Current '86 GT lockup vs non-lockup is only 100rpm at 60mph. And, it won't kick out of lockup when "right foot down" unless it downshifts to 2nd. After reading several threads on this, I'd guess something is not working as it should, but haven't been able to sort out "what" might not be right. I'm not impressed with the gas milage, 15-16 local, 20-21 highway, especially compared to our 91 Dodge minivan (3.3L) that gets 19-20 local, 25-26 highway. I'm trying to put "pieces" together from several threads, but can summarize as (a) want to increase milage, so (b) is there a tanny with a better final-drive ratio and lock up (is "TCC" a synonym for the lockup torque converter?), because I think the current lockup is not working as it should and the final-drive ratio is (from what I can find) 3.65/1. I've seen reference to a 4T60 transmission that appears to have a better final-drive ratio (3.3/1?). Is this a straight bolt-in replacement for the auto in the GT? I'm not interested in replacing the 2.8 with another engine (except maybe a six-cycle phased-vane rotary -- but that's another story) as it has enough performance for my needs. I am willing to change the tranny though so long as it is a "plug and play" bolt-in task.
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10:47 PM
May 24th, 2006
matt_p182 Member
Posts: 45 From: Silverdale, Wa USA Registered: Jan 2006
One other thing that comes into play on shifting speeds. The throttle valve (tv) cable. If it's out of adjustment, stretched, or fraying it will cause variations in the shifting speeds and quality. I don't know how much it could affect the tcc.
Well i dont know of all of this is due to my EGR tube being cracked or suspected malfunctioning TCC but here are the symptoms i have.... 85GT BTW
Sometimes when I start the car it will stall, when it is running sometime right when i put it into gear it will stall over and over again. usually happens more when engine is warm. To finally get her in gear i have to have my foot on the gas. When i have to hold my foot on the gas and I start driving like in a parking lot i have to hit second from the idle to settle down, if i dont hit second sometimes if im at a stop sign the engine will just stall, but if the car shifts into second before i reach the stop sign it is fine. Another probnlem is around 35-45 mph just cruising the car will buck pretty hard maybe like the TCC engaging and disengaging, i think its transmission related because when it bucks the tachometer doesnt move. And sometimes crusing at highway speeds if i hit the brakes the TCC will kick down and engage again.Other times it wont and i dont know how to make it, bt if i try later on in the drive sometimes it will work. Also when i floor it from a stop it will shift into the TCC mode around 3200rpm in third gear still at full throttle. once the car reaches third pretty much the car shifts into TCC mode. I dont know where to begin solving this.
